Horizontal hoppers are used to provide a continuous supply of cartons, boxes, cardboard ribs, or other packaging blanks to operational packaging machinery. Typically, such hoppers support an array of folded packaging blanks in a predetermined orientation. Lead packaging blanks are removed periodically from the array by movable vacuum arms or the like which transfer the lead blank to an assembly conveyor where subsequent operations are carried out on the blanks. The hopper must insure that a new blank is in proper position for removal by the vacuum transfer mechanism during each blank delivery cycle. Additionally, the hopper should have sufficient capacity to support a large number of packaging blanks so that the hopper does not need to be frequently reloaded.
Two design considerations in hoppers are that the hopper (1) support a large number of packaging blanks and (2) maintain the lead packaging blank at its proper delivery position. Oftentimes, the designs of horizontal hoppers has compromised one of these design considerations to satisfy the other. In hoppers with a large capacity, the leaning weight of a large horizontal array of packaging blanks typically applies undesired and varying pressure to the lead packaging blank. This pressure causes delivery errors. On the other hand, hoppers which maintain the lead packaging blank at its proper delivery position without undue pressure offer small capacity storage. This requires frequent reloading.
A third design consideration in such hoppers is the desire to make the supply of packaging blanks continuous relative to operation of the associated packaging machinery. Accordingly, a hopper should be designed to facilitate reloading of packaging blanks without affecting or halting the desired continuous feed operation.
U.S. Pat. No. 4,934,682 to Rece discloses an apparatus for feeding cartons which divides the array of cartons into two groups. The first group of cartons is advanced on a first feed conveyor to a delivery position so that lead cartons can be successively delivered for assembly. A second, larger group of cartons is supported and transferred on a second feed conveyor against an inclined stop in a position above the first conveyor and first group of cartons. A downward ramp separates the two conveyors and two groups of cartons. A sensor is employed to detect when the number of cartons in the first group diminishes to a predetermined level. Upon reaching this predetermined level, the cartons from the second group are transferred down the ramp to the first group of cartons. While the Rece patent disclosure satisfies many of the design considerations of a blank hopper, the Rece hopper requires many structural elements to separate the two groups of cartons, including the downward ramp and the inclined stop. These structural elements complicate operating effectiveness and add to the overall cost of the disclosed staging hopper.
U.S. Pat. No. 4,697,973 to Hahn, U.S. Pat. No. 3,598,399 to Cottrell, U.S. Pat. No. 3,391,806 to Gies, and U.S. Pat. No. 2,161,124 to Babicz disclose apparatuses for feeding folded cartons. These patents, like the Rece patent, describe staging hoppers which require additional structural elements for separating two groups of cartons.
The present invention accomplishes all of the design goals for staging hoppers while minimizing the structural components and cost of the hopper.